openvswitch: collect mega flow mask stats

Collect mega flow mask stats. ovs-dpctl show command can be used to
display them for debugging and performance tuning.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
diff --git a/net/openvswitch/flow_table.h b/net/openvswitch/flow_table.h
index 4db5f78..fbe45d5 100644
--- a/net/openvswitch/flow_table.h
+++ b/net/openvswitch/flow_table.h
@@ -66,10 +66,12 @@
 int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
 			struct sw_flow_mask *mask);
 void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow);
+int  ovs_flow_tbl_num_masks(const struct flow_table *table);
 struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *table,
 				       u32 *bucket, u32 *idx);
 struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *,
-				    const struct sw_flow_key *);
+				    const struct sw_flow_key *,
+				    u32 *n_mask_hit);
 
 bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
 			       struct sw_flow_match *match);